In The Swim 20 x 40 ft. Rectangle Micro Mesh Pool Winter Cover Micro mesh pool cover traps the finest silt and debris, preventing them from contaminating your pool Has reflective silver coating on the top to speed up the snow's melting process Hems are stitched with heavy-duty U.V. treated polypropylene thread to resist rot Pool cover has black underside to inhibit algae growth 8-Year Warranty (1 Year Full)